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1. Field of the Invention
This invention generally relates to wireless communications and, more particularly, to radio base stations that monitor cooling systems.
2. Description of the Related Art
Wireless communication has experienced explosive growth. In just a few years cellular telephone usage has soared, and growth continues as wireless Internet access improves. This explosive growth has revolutionized data and voice communication, and manufacturers are continually striving to improve wireless equipment to meet the explosive growth.
Radio base stations are one example of continuously improving wireless equipment. Radio base stations are self-contained enclosures that house transmitters, receivers, and other wireless communication equipment. While radio base stations were originally designed for indoor installations, explosive growth has forced manufacturers to design outdoor radio base stations. These outdoor radio base stations allow wireless service providers to improve service by expanding the coverage area.
These outdoor radio base stations, however, are prone to overheating. The wireless communication equipment generates high heat loads within the radio base station. Solar heat loads may also exacerbate internal temperatures within the radio base station. If the wireless communication equipment is exposed to temperatures lying outside an operating range, the equipment may fail from thermal stress. Some radio base stations, therefore, are equipped with air conditioners to keep the wireless communication equipment within the operating range. If the air conditioners fail, the wireless communication equipment overheats and fails. When the wireless communication equipment fails, wireless service is interrupted. An interruption in service irritates customers, disrupts daily business activities, and reduces revenue for the service provider.
Thermal stress is such a concern that some radio base stations have two air conditioners. Air conditioning unit #1 is generally designated a xe2x80x9cleadxe2x80x9d unit, while air conditioning unit #2 is a xe2x80x9clagxe2x80x9d unit. Unit #1 is then the primary cooling unit, while unit #2 is a secondary cooling unit. Unit #1 runs for a preset time and maintains the wireless communication equipment at a preset temperature. Unit #1, for example, may run for twenty four (24) hours and have its thermostat cool to a temperature of eighty degrees (80xc2x0). At the end of the preset time, say twenty four (24) hours, the two air conditioning units swap functions. Unit #2 now becomes the lead primary air conditioner, while unit #1 becomes the lagging secondary air conditioner. This xe2x80x9clead-lagxe2x80x9d operating scenario prevents either air conditioner from continually running and from prematurely wearing out.
The lead-lag operating scenario is also meant to improve cooling of the wireless communication equipment. If the lead air conditioning unit #1 experiences a problemxe2x80x94such as overloading, too much internal heat, or even failurexe2x80x94the lag air conditioning unit #2 then operates as a backup. If unit #1, for example, has its thermostat set at eighty degrees (80xc2x0), unit #2 would initiate cooling if the internal temperature rose to eighty five degrees (85xc2x0). The lag unit thus acts as a backup to the lead unit and helps prevent thermal overloads.
This lead-lag operating scenario, however, does not provide adequate notice of air conditioning failures. A field engineer must know, for example, when the lag air conditioning unit is operating. If the lag unit #2 is operating, then the lag unit #2 may be trying to overcome a heavy heat load. The lag unit #2, worse, may indicate the lead unit #1 has failed. If the lead unit #1 has failed, the lag unit #2 will constantly operate to cool the wireless communication equipment. The lag unit #2, the only working air conditioner, will eventually wear out and fail. The internal temperatures quickly rise, a high temperature alarm trips, and the wireless communication equipment shuts down and causes a communication outage. Only then are the field engineers alerted to the overheating problem. All the while the communication outage is disrupting personal and business activities.
The lack of adequate notice of air conditioning failures cascades to other problems. If the lead unit #1 has failed, and the lag unit #2 continually operates to failure, the wireless service equipment has shut down. Thousands of revenue-generating calls are lost per hour. An air conditioning specialist must be called to investigate the failure. Field engineers must accompany the air conditioning specialist. If the failure occurs on a weekend, a holiday, or an evening, overtime costs apply. Because both air conditioning units have failed, replacement parts, or even replacement units, could cost thousands of dollars. While the air conditioning specialist initiates a repair, the field engineer is setting up floor fans to cool the wireless communication equipment. These fans, however, draw dust and dirt and contaminate the wireless communication equipment. The lack of adequate notice of air conditioning failures, thus, cascades to multiple other problems.
There is, accordingly, a need in the art for a radio base station that has a reduced rate of thermal stress failures, a radio base station that alerts engineers of air conditioning problems or unusual operating conditions, and, yet, a radio base station design that can resolve the prior art problems without extensive revisions or large expenses.
The aforementioned problems are minimized by a radio base station that monitors its air conditioning system. This radio base station continuously monitors the air conditioning system in real-time. The radio base station alerts field personnel, engineers, or any other person when the air conditioning system operates. If the radio base station has two air conditioning systems, operating in the xe2x80x9clead-lagxe2x80x9d scenario, the radio base station may send an alert when either air conditioning system operates. This radio base station design, therefore, can notify personnel when the lagging, back-up air conditioning system operates, possibly indicating a problem with the lead, primary air conditioning system. The radio base station may then alert field engineers before both air conditioning systems prematurely fail.
The radio base station may also alert engineers and field personnel to other indications of the air conditioning system. The radio base station may send alerts indicating normal operation, errors, or even failures in the air conditioning system. The radio base station, for example, may simply communicate whether the air conditioning system is running. The radio base station could also communicate how much electricity is being used by the air conditioning system. If too much electricity is being consumed, the air conditioning system may have encountered an unusual operating condition. The radio base station could also monitor refrigerant pressures within the air conditioning system. A low refrigerant pressure could indicate a leak in a condenser/evaporator coil. The radio base station may monitor ambient temperatures and indicate unusual cold weather operation. If, for example, the air conditioning system is operating during cold ambient temperatures, ice may form on the condenser. The radio base station, in short, may send any status information, fault or error information, alarm information, or any other information useful for monitoring the operation of the air conditioning system.